1. Field of the Invention
The present invention relates to an apparatus for controlling power supply for use in a motor vehicle, and more particularly to an apparatus for controlling power supply for used in a motor vehicle which causes a lamp load to blink by power supply from a in-vehicle batter or power generator.
2. Description of the Related Art
A hazard lamp is an example of the lamp load which blinks by power supply from the in-vehicle battery or power generator. The hazard lamp serves to inform other vehicles that one""s own vehicle is parking. Therefore, the hazard lamp is often caused to blink for a long time when the engine is stopping and idling. Specifically, the hazard lamp is caused to blink for a long time when power is not generated by a power generator or when the power consumption by the hazard lamp is more than the power generated (even if the power generation is executed) i.e. when the charging of an in-vehicle battery is not entirely executed. Thus, there was a possibility that the remaining quantity of the battery lowers so that the engine cannot be started, i.e. battery is entirely discharged. Even when the battery is not discharged, there was a possibility that the remaining quantity of the battery lowers to the verge of discharging of the battery, and the battery is charged again when the engine is started. Such a repetition of the abrupt increase/decrease of the remaining quantity promotes the deterioration of the in-vehicle battery as compared with a normal case.
In order to obviate the discharging of the battery or the deterioration of the in-vehicle battery, there is proposed that if the hazard lamp continuously blinks for a prescribed period of time or longer, the light quantity is reduced so that the hazard lamp is caused to blink with reduced power. However, since the hazard lamp serves to inform other vehicles of the presence of one""s own vehicle, the hazard lamp is preferably caused to blink with no reduced light. Particularly, when one""s own vehicle parks on a road with a few street lamps at night, the hazard lamp is preferably conspicuous so that the blinking of the hazard lamp can be recognized by other vehicles located far away. However, in the light reduction of the hazard lamp at one step as described above, the light reduction is excessively carried out to cause the hazard lamp to blink by reduced power even when the remaining quantity of the invehicle battery is not lowered greatly such as when the blinking of the hazard lamp succeeds for a prescribed time. In this case, the power is saved exaggeratedly.
An object of the present invention is to provide an apparatus for controlling power supply for use in a vehicle which permits a lamp load to blink for a longer time without saving power excessively by stepwise reducing the power to be supplied to the lamp load according to the remaining quantity of an in-vehicle battery.
In order to attain the above object, in accordance with the invention, as shown in FIG. 1 showing the basic arrangement of the present invention, there is provided an apparatus for controlling power supply for use in a vehicle for causing a lamp load to blink by power supply from an in-vehicle battery 101 or generator ALT, comprising: means 100 for stepwise decreasing power to be supplied to the lamp load whenever a blinking time of the lamp load passes prescribed times.
In this configuration, the lamp load can blink for a longer time, and the power supply can be saved according to the remaining quantity of the battery.
Preferably, the lamp load is caused to blink by a pulse-like power source voltage, and the power decreasing means comprises means 104a for stepwise decreasing a duty ratio of the pulse-like voltage whenever the blinking time of the lamp load passes the prescribed times.
In this configuration, with the brightness of the lamp load being maintained, the power to be supplied to the lamp load can be easily saved.
Preferably, the duty ratio is decreased to a minimum value enough to recognize the lamp load visually. This avoids wasteful power consumption when the hazard lamp can not be visually recognized.
The above and other objects and features of the invention will be more apparent from the following description taken in conjunction with the accompanying drawings.